The 7A18 is a very common dual trace vertical amplifier plugin for the 7000 series mainframes. Its 75 MHz bandwidth can only be attained in an appropriate mainframe.

Option 06 was available, which adds dc offset circuits that provides ±200 divisions of baseline offset.

Tekwiki has the user manual.

Tektronix 7A18 Dual Trace Amplifier

Tektronix 7A18 Dual Trace Amplifier

Holland build!

Tektronix 7A18 Dual Trace Amplifier

Right view. Rear view of the amplifier board and readout boards.

Tektronix 7A18 Dual Trace Amplifier

Tektronix 7A18 Dual Trace Amplifier

Tektronix 7A18 Dual Trace Amplifier

Calibrated by Dick V. Thanks!

Tektronix 7A18 Dual Trace Amplifier

Left view. Front view of amplifier board and probe input circuit: attenuator and compensation.

Tektronix 7A18 Dual Trace Amplifier

Tektronix 7A18 Dual Trace Amplifier

Custom Tektronix part: 155-0022-00: channel switch. Or analog multiplexer; selects one of two differential analog inputs given a digital control signal. Basically current-steering switch. Used in ADD or CHOP display modes for simultaneous display of the two traces.

Tektronix 7A18 Dual Trace Amplifier

Thermally coupled bipolar transistors.

Tektronix 7A18 Dual Trace Amplifier

Overview of the amplifier board.

Tektronix 7A18 Dual Trace Amplifier